Reference

AlllOl 7261

NBSIR 79-1931

Fire Experiments and Flash Point

Criteria for Solar Heat Transfer

Liquids

B. T. Lee and W. D. Walton

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D.C. 20234

November 1979

Final Report

Prepared for Department of Energy

’ashington, D.C. 20545

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nq - /t/2 • FIRE EXPERIMENTS AND FLASH POINT

CRITERIA FOR SOLAR HEAT TRANSFER

LIQUIDS

B. T. Lee and W. D. Walton

Center for Fire Research

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D.C. 20234

November 1979

Final Report

Prepared for Department of Energy

Washington, D.C. 20545

U.S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Jr., Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

LIST OF TABLES

Page

Iv

LIST OF FIGURES iv

Abstract 1

1. INTRODUCTION 1

2. EXPERIMENTAL ARRANGEMENT 6

2.1 Flash Point 6

2.2 Room Fire Tests 6

2.2.1 Liquid Spill 7 2.2.2 Flowing Liquid Leak 8

2.3 Other Fire Tests 9

2.3.1 Spray Leak 9

2.3.2 Liquid Soaked Insulation 9

3. RESULTS AND DISCUSSION 9

3.1 Flash Point 9

3.2 Liquid Spill 10

3.3 Flowing Liquid Leak 11

3.4 Spray Leak 12

3.5 Liquid Soaked Insulation 12

4. SUMMARY OF EXPERIMENTAL FINDINGS 13

5. DEVELOPMENT OF CRITERIA 13

6. PROPOSED CRITERIA 15

7. ACKNOWLEDGMENTS 17

8. REFERENCES 17

iii
LIST OF TABLES

Page

Table 1. Flash point and fire points for some common solar heat

transfer liquids 19

Table 2. Experimental conditions for the five fluid spill cases 20

Table 3. Solar heat transfer fluids used in spray tests . . . , 21

Table 4. Case A fluid spill fires 22

Table 5. Case B fluid spill fires 23

Table 6. Case C fluid spill fires 24

Table 7. Case D fluid spill fires 25

Table 8. Case E fluid spill fires 26

Table 9. Fluid spill fires - ethylene glycol and ethylene

glycol-water mixtures 27

Table 10. Flowing fluid fire test (pilot flame only) - light

hydrocarbon oil 28

Table 11, Flowing fluid fire test (pilot flame only) - extractednaphthenic oil 29

Table 12. Flowing fluid fire test (pilot flame only) - polyalkylene glycol 30

Table 13. Flowing fluid fire tests (pilot flame only) - ethylene

glycol and glycol-water mixtures 31

Table 14. Flammability of fluid soaked insulation 32

LIST OF FIGURES

Page

Figure 1. Active solar energy system 33

Figure 2. Reduced scale room fire test 34

Figure 3. Fluid spill test pan with spiral gas burner in place . 34

Figure 4. Spray test setup 35

Figure 5. Correlation with flash point temperature 36

iv
FIRE EXPERIMENTS AND FLASH POINT CRITERIA

FOR SOLAR HEAT TRANSFER LIQUIDS

B. T. Lee and W. D. Walton

Abstract

To help provide a rational basis for developing

flammability criteria for heat transfer fluids used in

solar energy collection systems, fire tests were performed

using simulated accident scenarios involving spills,

flowing leaks, spray leaks, and soaked insulation. These

experiments indicated that the flash point temperatures,

as measured with the Pensky-Martens closed cup apparatus,

are close to the minimum temperatures at which pools of

the fluids will support a flame when they are exposed to

a small pilot igniting flame in a room. The heat release

from moderate sized burning pools of these liquids is

sufficient to cause flashover in a room.

Interim flash point criteria of at least 28 deg C

(50 deg F) greater than the maximum operating temperature

and not more than 111 deg C (200 deg F) below the maximum

no-flow temperature are proposed to reduce the risk of

fire in the use of solar heat transfer liquids.

Key words: Fire prevention; fire tests; flammability;

flash point; heat transfer fluids; insulation; leakage;

solar collectors; solar energy.

1. INTRODUCTION

As the nation becomes more concerned with energy conservation, the

use of solar heating and cooling systems is becoming increasingly popular.

Although solar heating is an important alternate form of energy, there

is no adequate standard addressing the safe use of combustible heat

transfer liquids in such systems for residential occupancies. Safety

standards are available for the general use and storage of flammable and

combustible liquids, including conventional heating fuels; but these

standards do not consider the particular problems of heat transfer

liquids in solar heating and cooling systems. Solar heating and cooling

is still basically a new technology even though systems have been

operational for some time. Since there has been no substantial research

in this area, performance criteria for flammable and combustible solar

heat transfer liquids have been difficult to set.

The terms defined below are used throughout the report, and pertain

to solar heating and cooling systems, to combustible and flammable

liquids and to fire phenomena.

1
Ambient temperature - The average air temperature in the testing

facility. During the tests reported here the ambient temperature

was 22 + 3°C (72 + 5°F)

Autoignition temperature - Temperature to which a closed or nearly

closed container must be heated in order that the liquid in question,

when introduced into the container, will ignite and burn in the

absence of a flame or glowing heat source. Time lags of a minute

or more are frequently involved. The standard test method for

autoignition temperature of petrolexom products is described in

^ ASTM D 2155, Autoignition Temperature of Petroleum Products [I] .

Collector - The assembly used for absorbing solar radiation,

converting it into useful thermal energy and transferring the

thermal energy to a heat transfer fluid.

Combustible liquid - Any liquid having a flash point at or above

37.8°C (100°F) I2J.

Fire point - The lowest temperature of a liquid in an open container

at which vapors are evolved fast enough to support continuous

combustion. The fire point is higher than the flash point [1].

Flammable liquid - Any liquid having a flash point below 37.8°C

(100“F) 12].

Flash point - The minimum temperature of a liquid at which sufficient

vapor is given off to form an ignitable mixture with the air near

its surface. The flash point is determined by a specified test

procedure and apparatus [1]. Four standard methods are available

for measuring flash point:

Flash Point Range

(1) Pensky-Martens closed cup ASTM D 93 ^ 93° C (200°T)

(2) Cleveland open cup ASTM D 92 > 79°C (175°F)

(3) Tag closed cup ASTM D 56 < 93.4°C (200°F)

(4) Tag open cup ASTM D 1310 -17.8° to 168°C (0 to 325°F)

The method used depends on the flash point range and viscosity of

the liquid and whether an open or closed cup test is appropriate or specified. NFPA No. 321, Basic Classification of Flammable and

Combustible Liquids [2], specifies closed cup only. Open cup flash

points are sometimes used in grading flammable liquids in transportation [1], It should be noted that the flash point varies with

the pressure and oxygen content of the atmosphere, with the purity

of the product being tested, with the method of test, and with the

skill of the operator running the test [1].

Numbers in brackets refer to the literature references listed at the end

of this report.

2
Flameover - The fire condition in which flames reach out of the

doorway of the fire room,

Flashover - The fire condition in which the thermal radiation level

in a room becomes high enough to ignite remote combustible materials

such as newspaper and upholstered furniture in the lower half of

the room.

Heat transfer liquid - The operating or thermal storage liquid used

to transfer heat from the collector to the storage or heat exchanger

system. Typically, it consists of water or other liquid base and

all additives at the concentration used under operating conditions.

Insolation - The incident solar energy, often expressed as heat

flow rate per unit horizontal surface.

No-flow temperature - The average temperature of the heat transfer

fluid in the collector when the fluid is not moving. The design

maximum no-flow temperature is the liquid temperature under design

conditions of insolation and outdoor air temperature which cause

the highest collector temperature at a given site. Typical no-flow

temperatures for residential heating systems vary from 120°C (248®F)

to 230“C (446“F) and from 175°C (347®F) to 370®C (698°F) for

cooling systems.

Operating temperature (Flow temperature) - The average temperature

of the heat transfer liquid in the solar heating system under

normal operating conditions; typically, this ranges from 20°C

(68®F) to 90°C (194®F) for residential heating systems and from

90®C (194®F) to 150“C (302®F) for cooling systems. The design

maximum operating temperature is the liquid temperature measured at

the collector outlet, or manifold, under the conditions of insolation and outdoor air temperature which cause the highest operating

temperature at a given site. For systems involving multiple fluid

loops this temperature is taken to be the maximum attained in any

loop under the conditions stated above.

Solar energy system, active - A system which may include collectors,

thermal storage heat transfer fluid and load, and which utilizes

solar energy for heating and/or cooling and in which all fluid

flows are by forced means (pumps or fans) [7],

Solar energy system, hybrid - A system which may include collectors,

thermal storage, heat transfer and load, and which utilizes solar

energy or environmental energy sinks for heating and/or cooling and

in which at least one energy flow is by forced means and at least

one is by natural means [ 7 ]

.

Solar energy system, passive - A system which may include collector,

thermal storage, heat transfer fluid and load, and which utilizes

solar energy and fluid or environmental energy sinks for heating

3
and/or cooling and in which all energy flows are by natural means

(conduction, convection, radiation, or evaporation) [7].

It is difficult to characterize a "typical” solar energy system

because of variations in factors such as climate, system design and

efficiency, size of the building to be served, and the percent of the

total energy load the solar system is expected to provide. For a single

family residence the solar system may be designed to provide domestic

hot water, space heating or both. Figure 1 shows a representative

active system configuration. A domestic hot water system would generally

contain from 4 to 11 square meters (40 to 120 ft^) of collector area and

a space heating system from 9 to 74 square meters (100 to 800 ft^) of

collector area. An average collector has an area of 2 square meters

(20 ft^) and contains approximately 2 liters (1/2 gal) of heat transfer

fluid. In terms of overall system fluid capacity including collectors,

piping and heat exchanges a hot water system would typically contain 19

to 38 liters (5 to 10 gal) of heat transfer fluid and a space heating

system 38 to 189 liters (10 to 50 gal) of fluid. In addition to the

heat transfer liquid the solar energy system may contain a thermal

storage fluid which is typically water. The amount of thermal storage

fluid may range into the thousands of liters if the storage is expected

to carry the heating load for an extended period of time during which

the system can collect little dr no solar energy.

The fire hazard of a particular process or occupancy may be evaluated

by the development of potential fire scenarios that approximate actual

use conditions. Scenarios are usually based on an evaluation of statistical data on fire frequency and cause if such data are available. If an adequate data base does not exist, the scenarios must be based on judgment and the limited data that are available. In the present case,

a suitable data base is not available for fire occurring in conjunction

with solar heating systems. Therefore, the development of fire occurrence

scenarios and the determination of the protection required are based on our experience and judgment. This technique has been chosen in an attempt to anticipate potential fire problems and to suggest an acceptable

level of safety.

The examination of fire occurrence scenarios pertains primarily to

active solar energy systems and the active portion of hybrid systems

since these are the systems which normally contain combustible heat

transfer liquids. Ideally solar heating and cooling systems should not

leak under normal operation; however, experience with existing solar

installations has indicated a substantial number of leaks will occur. Thus, in the scenarios selected, a leak in the collector piping system

results in the discharge of the heat transfer liquid at a temperature

greater than that of the surrounding air. If the liquid is a flammable

or combustible liquid and the temperature is sufficiently high, flammable

vapors will be produced which may be ignited by an available ignition

source. There are several important variations, such as the location

and nature of the fluid leak or discharge and whether the system is in an operating or no-flow mode. Specifically these scenarios could involve:

4
(1) a pipe break which results in a substantial leak spilling on the

floor and forming a liquid pool, or a drip from a loose pipe connection,

faulty pump packing, partially open drain, etc., which over a period of

time could result in a pool of the liquid on the floor, (2) a substantial

leak occurring in the piping network away from the collector area while

the system is in the no-flow condition, where one would expect the

discharge of some liquid, which was contained in the pipes at close to

the operating temperature, followed by hotter liquid from the collectors,

and (3) a small leak under high pressure causing a spray or mist. If

the spray should occur in the attic space, thermal insulation might be

soaked with the fluid, posing an additional potential fire problem.

Incorporated in the evaluation of each scenario is the presence of an ignition source. There is a high probability that a non-hostile

ignition source will exist in a building at the time of a leak. A nonhostile ignition source is one associated with the normal operation of

appliances or normal activities. This would include pilot flames or burners in heating appliances, electric resistance heating elements,

sparks from electrical appliances and switches, fires in fireplaces and

stoves, smoking materials, etc. An incidental fire may also occur; this

is one which is not a normal occurrence and will not result, by itself,

in total fire involvement of a room or building. Nevertheless it is

desirable that leaks and spills of the heat transfer fluid adjacent to or in the vicinity of such fires would not easily contribute to the fire

growth.

In this study no attempt has been made to provide for the hazards

resulting from welding, cutting, soldering or brazing pipes and other

components which contain combustible liquids. Standard methods for

reducing these hazards are available and are the responsibility of the

individuals engaged in such operations. In addition, the problem of

intentionally set fires or relatively unusual occurrences, such as lightning strikes, have not been addressed.

The objective of this project is to provide an experimental basis

for specifying flammability test standards for the heat transfer liquids

used in solar heating systems and recommend such standards.

The closed cup flash point was selected for the presentation and

correlation of the data. The open cup flash point and fire point could

also be used for this purpose. The autolgnltion temperature is a property

of a fluid that can be measured, but has not been judged useful as a measure of the fire hazard of liquids for solar heating and cooling

systems. The autoignition temperature is most useful for determining

the ignition susceptibility of liquids in contact with hot surfaces in

the absence of a pilot ignition source. Some liquids with very high

autoignition temperatures produce flammable vapors below a temperature

of 0°C. These vapors may travel considerable distances and are easily

ignited by a spark or flame.

Other factors are important in evaluating the overall performance

of a flammable or combustible liquid. These include the flammable

5
limits, rate of evaporation, density and rate of diffusion of the vapors,

specific gravity, boiling point, water solubility, and effective heat of

combustion. Although these factors are Important for evaluating explosion

potential, burning rate, extinguishabllity and a variety of other conditions, the susceptibility to ignition is the most important property for

evaluating solar heat transfer fluids.

2. EXPERIMENTAL ARRANGEMENT

As previously described, several fire scenarios involving leaks and

spills of these heat transfer fluids were considered for the fire tests.

The accident scenarios employed can be categorized briefly as follows:

(1) floor spills of these fluids in a room in combination with an incidental fire nearby or with a flame in contact with the fluid, (2) flowing

fluid leaks and liquid spray leaks in the presence of pilot flames in a room but in the absence of an incidental fire, and (3) liquid spray leaks

on attic insulation with subsequent non-host ile flame ignition. With a floor spill the hot fluid is heated by the fire and cooled by contact

with the floor. As the fluid continues to spill, the heat losses to the

floor would decrease and the fluid could, in some cases, remain close to

the flash point temperature. Flames in contact with the fluid might

then spread across it and produce heat release rates sufficient to

produce flashover of the room. The floor spill scenarios were studied

in detail to examine the role of flash point in room fire growth under a variety of fire exposure conditions. A flowing leak could involve a hot

fluid at the operating temperature discharging through a break in the

system onto a dry ambient temperature surface. If the system were in

the no-flow mode, this discharge could be followed by a hotter fluid

originally at the stagnation temperature in the collector. Discharges

of the hot liquid onto a dry ambient temperature surface and into a pool

of the same liquid were both studied. Replicate fire tests were not

performed due to cost and time limitations and the large number of fire

scenarios examined.

2.1 Flash Point

The flash points of ten commonly used solar heat transfer liquids

shown in table 1 were measured with the Pensky-Martens closed cup test [3]

and for comparison the flash points and fire points were also measured

with the Cleveland open cup test [4]. Eight of these fluids, indicated

in the table, were selected for the research study. The alkylated

aromatic and diphenyl-diphenyl oxide were excluded from further study as they were considered too toxic to handle safely in the available fire

test facility. In addition, a light hydrocarbon oil, also shown in the

table, having low flash point was included in the investigation for

comparison purposes and to extend the flash point range.

2.2 Room Fire Tests

In order to assess the potential fire hazard Introduced by the

spilled or flowing liquid, it is appropriate to burn it in a room where

6
the burning rate of the liquid will be affected by radiation feedback

from the flames of an existing fire or from the high temperatures in the

room. A fire in a room raises the temperature of the air and the temperature of the room surfaces. This causes a rise in the thermal radiation

levels in the room resulting in an increase in the burning rate of the

liquid. If there is a sufficient increase in the rate of combustion,

the room will flashover and the integrity of the building will be

threatened

.

Three full-scale room fire tests were performed, and these involved

flowing fluid leak fires. All other fire tests on fluid spills and

flowing fluid leaks were conducted in a one quarter-scale room having

dimensions of 0.75 x 0.75 x 0.6 m (2.5 x 2.5 x 2 ft) high based on reduced scale modeling techniques developed at NBS [5,6] to study fire

growth in rooms. Although all relevant parameters cannot be scaled, the

model provides a reasonable approximation of the behavior of a full-scale

room fire. The one quarter-scale room has been used successfully to

characterize fires involving a variety of materials and was adopted for

this program for economy and convenience in testing.

2.2.1 Liquid Spill

The following five cases were selected for testing:

Case (A) Fluid at a temperature 28 deg C (50 deg F) below its

flash point with a large (6 kW) flame in contact with the

spill.

Case (B) Fluid at a temperature 56 deg C (100 deg F) below its

flash point with various sized (1.5 to 6 kW) flames in contact

with the spill.

Case (C) Fluid at a temperature 56 deg C (100 deg F) below its

flash point with a large (6 kW) Isolated incidental fire in

the room and a small pilot flame in contact with the spill.

Case (D) Fluid at ambient temperature with a large (6 kW) flame in

contact with the spill.

Case (E) Fluid at ambient temperature with a large (12 kW) Isolated

incidental fire in the room and a small pilot flame above the

spill.

The test conditions are summarized in table 2.

The fire tests were performed in a one quarter-scale room constructed

from one-inch thick ceramic flberboard. This box has the dimensions of

76 X 76 X 61 cm (30 x 30 x 24 in) high and an opened doorway and is

shown on figure 2. About 1450 ml of each fluid tested was poured to a depth of 0.52 cm (0.20 in) in a 38 x 74 cm (15 x 29 in) pan situated on

the floor along one side wall of the room. This situation corresponded

to 23 1 (6 gal) of the liquid covering half of the floor area at a depth

7
of 0.52 cm (0.20 In) in a 3 x 3 m (10 x 10 ft) room. The basis for the

scaling of the liquid spill was assumed to be the same as that used for

the modeling of the room fire tests of interior finish materials [5].

Briefly stated, the modeling rules required that the quantity of material

must vary in direct proportion to the floor area and the thickness of

the material must not change.

Two electric "kitchen range" spiral heaters, positioned under the

pan, were used to heat the liquid to the desired temperature. A gas

spiral burner, 7.6 cm (3 in) wide, made from 0.32 cm (1/8-in) copper

tubing having holes drilled along its top side, served as the igniter

contact flame. The burner operated at heat release rates from 1.5 to

6 kw (1.5 to 6 Btu/s) and was positioned in a depression at the middle

of the pan, shown on figure 3, and laid just submerged below the surface

of the fluid. For the 0.3 kw (0.3 Btu/s) contact flame a 0.32 cm (1/8-in)

diameter submerged tube gas burner was employed. Thermocouples were

located in the fluid 3.2 cm (1-1/4 in) in back of and 3.2 cm (1-1/4 in)

in front of the igniter flame. A 7.6 x 7.6 cm (3 x 3 in) reinforcement

gas burner, simulating an isolated fire in the room, was located in the

back corner away from the pan. Times for the occurrence of flashing in

the pan, flameover and flashover were recorded for each test. The tests

were terminated in Cases A and B if flashover had not occurred in 10

minutes. In Cases C, D and E, the tests were allowed to run for 15

minutes. The heat release rates of 12, 6, 3 and 1.5 kw (12, 6, 3,

1.5 Btu/s), corresponding to methane gas flow rates of 320, 160, 80 and

40 ml/sec (40, 20, 10 and 5 CFH) , respectively, used for the gas burners

in these tests were assumed to roughly correspond to the burning rates

of a large upholstered chair, a small upholstered chair, a large

wastebasket, and a small wastebasket, respectively, in a 3x3x2. 4m

(10 X 10 X 8 ft) high room.

2.2.2 Flowing Liquid Leak

Ethylene glycol, extracted naphthenic oil, polyalkylene glycol and a control fluid (light hydrocarbon oil) having closed cup flash points of

118, 138, 249 and 52®C (245, 280, 480 and 125°F), respectively, were

selected along with several ethylene glycol-water mixtures for this

phase of the work. Each fluid was preheated to a temperature above the

flash point in a tank and was released through an open pipe into a pan

lined with vinyl asbestos tile on the floor of a one quarter-scale model

room with an open doorway. With the ethylene glycol-water mixtures the

fluids were preheated above the flash point of ethylene glycol. A small

pilot flame was employed near the spill. The temperatures in the tank,

at the discharge end of the pipe, and in the spill were monitored. The

discharge temperature was varied for each fluid in order to establish

the critical temperature, required at the discharge and spill locations,

for flashing to occur.

In addition to the tests in the one quarter-scale room, one fire test

of the light hydrocarbon oil and two tests of an ethylene glycol-water

mixture having an initial 90% glycol fraction were conducted in a larger

8
test room having dimensions of 2. lx 2. lx 1.7 m (7 x 7 x 5.6 ft) high.

These tests in a larger room were intended to show the effect of room

size on the fire development and to verify the use of the smaller scale

tests as a simulation of the larger scale tests. In the one quarter-scale

test, 1450 ml of the test fluid was allowed to drain into the pan over a one-minute period, while 11 300 ml was used in the larger room test over

the same time period. The quantity of fluid used in the larger room

fire was increased in proportion to the floor area [5,6]. If flashing

occurred within this period, the test was allowed to continue for another

5 minutes following the one-minute discharge of fluid to evaluate the

potential for room flashover.

2.3 Other Fire Tests

2.3.1 Spray Leak

Spray leak tests were conducted on the fluids shown in table 3.

Two spray nozzles connected to an oil pump operating at 1170 kPa (170 psig)

were used for these tests. One nozzle was a standard oil burner type

rated at 0.89 ml/sec (0.85 gph) with a 90 degree spray angle and was used for producing the fine mist. The other nozzle was fabricated from

0.64 cm (0.25 in) copper tubing with an end cap having three number 80

drill holes and was designed to give a coarse spray. Each nozzle sprayed

downward with the spray envelope having a more concentrated spray at its

center axis than at its outer edges. Three pilot flames were positioned

such that the center and both edges of the spray envelope were exposed

to the flames. These tests were designed to evaluate the ignitability

of the fluids with either fine or coarse spray patterns. Figure 4 shows

the spray test setup. Both nozzles were used with the fluids operating

at ambient temperature.

2.3.2 Liquid Soaked Insulation

All of the heat transfer fluids shown in table 3 except the 50%

ethylene glycol-50% water mixture, two ethylene glycol-water mixtures

having 90% and 95% glycol fractions and the light heating oil were used

in these tests. Sections of 48 kg/m^ (3 Ib/ft^) fibrous glass batting,

38 X 104 X 7.6 cm (15 x 41 x 3 in) in size, were sprayed with 5 and 15 ml

of each fluid using a siphon type paint spray gun operating at 21 kPa

(3 psig) and then ignited along one end with a propane torch. The

distance of flame spread along the length of each specimen was noted.

Time was also recorded for flame travel to the opposite end of a specimen

whenever this occurred.

3. RESULTS AND DISCUSSION

3.1 Flash Point

The flash point and fire point measurements for the solar heat

transfer liquids considered in this study are shown in table 1. Measured

values for a light hydrocarbon oil are Included for comparison purposes.

9
The liquids are listed in the order of increasing flash point temperature

as measured with the Pensky-Martens closed cup test. In general, the

results indicated that a listing of the liquids according to increasing

values of open cup flash point or fire point did not differ appreciably

from the sequence given in table 1.

3.2 Liquid Spill

The results of the fire tests of fluid spills in a room, whose test

conditions are outlined in section 2.2.1, are indicated in tables A to 9.

The data for Case A, indicated in table 4, showed that all of the liquids

heated to 28 deg C (50 deg F) below their flash points experienced

flashing and resulted in a room flashover within 10 minutes of fire

exposure. Figure 5 shows that flash points of the fluids, as measured

with the Pensky-Martens closed cup test, correlated reasonably well with

their observed temperatures for flashing in the Case A tests. Much of

the scatter in the data probably resulted from difficulties in measuring

the fluid temperature at which flashing occurred in the room fire tests.

Fluid temperatures were measured at two sites, and unless flashing first

occurred at these sites the temperatures recorded at the onset of flashing

could be too low. When flashing occurred at one of the thermocouple

sites, it occasionally could not be visually detected until several

seconds later when the temperature was somewhat higher. The flickering

light from the gas burner and its reflection from the liquid pool tended

to obscure the observation of flashing. Part of the scatter in figure 5

may be due to thermal gradients in the liquid. With the exception of

the silicone oil, the higher the flash point the longer was the time for

the onset of flashing. The times for room flashover for all of the heat

transfer fluids, including the silicone oil, appeared to generally

increase with Increasing closed cup flash point values.

In Cases B and C, with the liquid at 56 deg C (100 deg F) below the

flash point, the data in tables 5 and 6 again showed that the flash

point appeared to correlate with the liquid's potential for flashing and

contribution to room flashover. The recorded temperatures for flashing

in these tests are also shown in figure 5. These temperatures correlated

well with the closed cup flash point measurements for the fluids. As

for the liquid's contribution to room flashover in the Case B tests,

liquids with flash points above 207“C (405**F) did not lead to flashover

within 10 minutes with a 6 kw (6 Btu/s) flame contact. At the intermediate flame setting of 3 kw (3 Btu/s) , all of the tests having liquids

with flash points at or above 199“C (390®F) did not result in room flashover within a 10-minute period. For the Case C tests, the data

indicated that liquids having flash points at and above 163“C (325®F)

would not lead to flashover within 10 minutes for this type of fire

exposure. The data in tables 7 and 8 are for Cases D and E where the

heat transfer liquids were originally at ambient temperature. For Case D,

where an incidental fire is inside the spill area, liquids with flash

points at and above 118**C (245®F) did not experience flashing and room flashover within 10 minutes. The data for Case E showed that the liquids

10
having flash points at and below 138°C (280°F) experience flashing and

room flashover within approximately 10 minutes when exposed to a moderately large isolated fire in the room.

Ethylene glycol-water mixtures were also tested in this study.

This work has indicated that when such mixtures are heated the water

component evaporates faster than the glycol fraction and that only

mixtures having a final glycol fraction greater than approximately 95%

have flash points. Table 9 compares the performance of two mixtures

with pure ethylene glycol for Cases A and B. Unless the mixture was predominantly ethylene glycol it did not flash within 10 minutes under

these fire conditions. Flashover was achieved for an initial mixture of

75% ethylene glycol with the mixture originally at 28 deg C (50 deg F)

below the flash point for pure ethylene glycol. For 100% ethylene

glycol, flashover was achieved with the fluid originally at 56 deg C

(100 deg F) below the flash point.

3.3 Flowing Liquid Leak

Test data on the flowing leak fires for the light hydrocarbon oil,

naphthenic oil and polyalkylene glycol are presented on tables 10 to 12.

These results indicated that unless fluids have fairly high flash point

values, the fluids will flash and lead to room flashover when the fluid

flowing between the pipe discharge and spill locations is in the vicinity

of the flash point temperature of the fluid. Tests with the polyalkylene

glycol, having a flash point of 249°C (480°F) , showed that flashing can occur with fluids having high flash points but that it may not be sus- tained and may not lead to flashover even when the discharge and pan

temperatures exceed the flash point temperature. The data in table 10

also show the time to flashing varies widely for small changes in the

discharge temperature. This indicates the discharge temperatures

selected were in the region of a critical point in terms of time to

flashing. This effect may be due in part to slight changes in ambient

conditions between tests.

Table 13 summarizes the results of the fire tests of flowing leaks

of ethylene glycol and ethylene glycol-water mixtures. In the tests

with the ethylene glycol, the liquid was heated to three different tank

temperatures above its flash point before it was discharged. The time

for flashing was found to decrease for increasing tank temperature with

the discharge temperature close to the flash point at the time of flashing

in all three cases. For the fire tests with the glycol-water, the mixture was allowed to boil and Increase further in temperature in order to

increase the probability for flashing when it flowed over the test pan.

However, in boiling the mixture, the water component evaporated more

quickly than did the glycol fraction and the composition of the liquid

became more concentrated with glycol. The data in table 13 showed that

the boiling temperatures increased slowly with time. It took roughly 10

to 15 minutes to increase the temperature by 10 to 20 deg C (18 to

36 deg F) , resulting in an increase of the glycol component of 5 to 10%

by volume. The composition of two of the glycol-water mixtures at the

11
time of flashing was determined by analyzing samples of the liquid taken

at the point of discharge and at the pan surface. The samples were

quickly cooled in a cold water bath and then were cooled further in an ethanol-dry ice bath to determine their freezing points. The latter are functions of the composition of the mixtures and thus can be used to

indicate the glycol fraction of the liquids. Only those mixtures having

an initial glycol fraction of at least 90% resulted in flashing under

the conditions tested. Analysis of the mixtures at the time of flashing

indicated glycol fractions of at least 95% and fluid temperatures of over 139®C (282°F) . With ethylene glycol and the glycol-water mixtures,

flashing of the liquid in every case led to fire involvement of the

entire pan of liquid within 30 seconds and to flashover of the room

within 100 seconds.

Results of the fire tests of the flowing liquid in the larger size

room, shown in tables 10 and 13, showed no significant differences in

the temperatures at the time of flashing due to room size. The number

of experiments was not sufficient to correlate room size with time to

flashover. With the light hydrocarbon oil the discharge temperature in

the larger fire test was 13 deg C (23 deg F) higher than the liquid used

with the smaller room test and, as expected, flashing of the oil and

room flashover occurred sooner. In the tests with the initial 90%

ethylene glycol-10% water mixture, the liquid took 14 to 18 seconds to

flash in the two small room tests and 3 seconds in the larger room fire

test. However, in a repeat of the same larger room test with similar

discharge temperatures but with a 8 deg C (14 deg F) lower tank

temperature, the liquid did not flash during the discharge period of one

minute.

3.4 Spray Leak

All of the heat transfer liquids used for the spray fire tests,

shown in table 3, ignited immediately upon contact with the pilot flames

with the exceptions of the 50% ethylene glycol-50% water mixture and the

paraffinic oil having a flash point of 207°C (405°F). This oil was very

viscous and tended to squirt and discharge in a stream with the fine and

heavy spray nozzles, respectively. The ethylene glycol-water mixture

tended to ignite only in the vicinity of the pilot flames and the

ignition was not sustained.

3.5 Liquid Soaked Insulation

The results of the liquid soaked insulation tests are given in

table 14. In the sprayed specimens tested after a wait of three days,

the time for flame to spread along the entire length of the specimen

increased with increasing flash point of the liquid with the times

varying from 13 to 45 seconds for the liquids having flash points from

135°C (275°F) to 285®C (545°F) . The two exceptions were the light oil

and the ethylene glycol. These liquids evaporated from the insulation

over the waiting period, and consequently the test specimens would not

support flame spread. Insulations coated with these two liquids along

12
with specimens sprayed with two glycol-water mixtures were also tested

at about 5 minutes after being sprayed. Flame spread to the end of the

insulation coated with the light oil took only 9 seconds while the

insulations sprayed with the ethylene glycol and glycol-water mixtures

took about 3 minutes for the same flame spread distance. The data also

showed that insulation coated with three times as much liquid experienced

a slower flame spread.

4. SUMMARY OF EXPERIMENTAL FINDINGS

Room fire tests of solar liquids indicate that:

1. Liquids will flash in the presence of a nearby pilot flame,

similar to that in a water heater, when their temperatures are

in the vicinity of the closed cup flash point values for the

liquids.

2. The liquids tested, with the exception of some ethylene glycolwater mixtures, will ignite and lead to room flashover when

the fluid covers one half of the floor area and is exposed to a moderate contact flame, equivalent to an upholstered chair.

3. The liquids tested, with the exception of some ethylene

glycol-water mixtures and the paraffinic oil having a flash

point of 207“C (405®F), will ignite immediately when sprayed

into a pilot flame.

4. Ethylene glycol-water mixtures must have a glycol fraction of

approximately 95% by volxime before flashing can occur in the

presence of a pilot flame.

5. The rate of flame spread along fibrous glass insulation sprayed

with the solar heat transfer fluids was higher for liquids

having low flash point temperatures.

5.

DEVELOPMENT OF CRITERIA

The sustained ignition of a liquid pool of the heat transfer liquid

within a structure is considered an unacceptable condition since it can result in the generation of heat, smoke and toxic products of combustion

leading to the spread of fire and to untenable conditions. The fire

tests have demonstrated that sustained ignition of these liquids will

occur in a room when they are at or above their closed cup flash point

temperatures. These results indicate that the closed cup flash point is

a suitable basis for the criteria which are consistent with NFPA No. 321.

Since the ignition of the heat transfer liquid is unacceptable and ignition sources are likely to be present, the temperature of the liquid

must be below the flash point if it is accidentally discharged into a building.

13
A rational analysis of the potential accident scenarios can contribute significantly to the development of the criteria. For the case of a leak in the piping system resulting in a pool of liquid the

system may be in operation with all of the liquid at the maximum operating

temperature. Since the liquid may discharge rapidly and have little

time to cool, the liquid should have a flash point significantly above

its operating temperature in order to avoid ignition. A safety factor

should be provided to allow for tolerances in the prediction and control

of maximum operating temperature. In this case the closed cup flash

point should be at least 28 deg C (50 deg F) greater than the maximum

operating temperature in order to provide a margin of safety so that a non-host ile ignition source would not Ignite a liquid spill even with

some localized heating. The 28 deg C (50 deg F) safety allowance may

not provide protection for liquids exposed to a moderate size or larger

ignition source. The tests have indicated that any liquid with a flash

point can be ignited when exposed to a sufficiently large ignition

source. The criteria could have been based on the open cup flash point

or fire point with the use of a different safety factor.

For comparison purposes, the flash point of home heating oil is

approximately 28 deg C (50 deg F) greater than normal ambient temperature.

The proposed requirement is designed to provide a level of safety for

solar heating systems which is basically equivalent to the level of

safety found in most home oil heating systems.

If a substantial leak occurs in the piping network away from the

collector area while the system is in the no-flow condition, one would

expect the discharge of some liquid which was contained in the pipes at

close to the operating temperature, followed by the liquid from the

collectors. The liquid from the collectors will cool as it moves through

the piping system towards the discharge point. The rate of cooling will

be a function of the heat transfer characteristics of the piping system,

the quantity of liquid in the collectors and the liquid transit time

between the collectors and the discharge point. In addition, if a pool

of liquid forms below the discharge point, the liquid from the collectors

will mix with the liquid from the piping creating a mixture with a temperature between that of the two liquids. In order to reduce the

probability that the temperature of the mixture is above the flash

point, the no-flow temperature should only be permitted to exceed the

flash point by a limited temperature difference. Although this maximum

temperature difference will vary from system to system and with the

location of the leak for a given system, it is desirable to have a single specified temperature difference rather than a complex calculation scheme. A panel of fire experts agreed on a temperature difference

of 111 deg C (200 deg F) for the case where the collector manifold

assembly is located outside of the building and exposed to the weather.

If a leak occurs in the collector or in the piping network in the

vicinity of the collector while the system is in the no-flow condition,

the liquid would discharge at approximately the no-flow temperature. It

is expected that most leaks will occur in the manifold piping connecting

14
the collectors rather than in the collectors themselves. If the manifold

piping is outside of the building, the leaking fluid would normally cool

substantially even if it were to subsequently enter the structure. This

includes situations in which the manifold is outside the building with a single pipe run leaving the manifold and entering the structure. The

ignition of the liquid on the roof from external sources is considered

relatively unlikely.

If the manifold piping is exposed within the interior of the

building, a leak in this piping would introduce liquid at the no-flow

temperature directly into the structure. The condition may be more

hazardous in attic areas where higher ambient temperatures could reduce

the normal rate of liquid cooling. To reduce the possibility of ignition

of the liquid leaking from collector manifolds which are inside the

building, the maximum no-flow temperature should not exceed the flash

point of the liquid.

In the case of a spray leak in the piping system, the fire tests

showed that when a spray is discharging directly into a flaming ignition

source, the high area to mass ratio of the liquid particles will result

in rapid heating and ignition of the liquid even when a relatively high

flash point liquid is involved. If the spray occurred in the attic the

insulation soaked with the liquid provides an additional potential fire

problem. However, the probability of a spray leak directly into a flame

or of the soaked insulation coming in contact with a flame is estimated

to be rather low.

Another type of system discharge is the operation of a pressure

relief valve or the opening of a drain or fill point. Systems using

non-potable heat transfer liquids will frequently be required to have

pressure relief valves and catchment basins connected to drains. Liquid

discharging into a catchment basin or sewer system will cool rapidly.

If a catchment basin is not provided, the previous scenarios should

adequately cover the discharge from a drain or pressure relief valves.

This discharge may be in the form of a spray, drip, or substantial leak

with the system in either the operating or no-flow condition.

6 . PROPOSED CRITERIA

Based on the results of the fire tests and of the analysis of

potential accident scenarios in this investigation and in a related

study 17], the following proposed interim acceptance criteria for solar

heat transfer liquids are recommended:

Criteria

Liquid flash point . The flash point of a heat transfer liquid

shall equal or exceed the higher temperature as determined by A and

B below.

15
A. 28 deg C (50 deg F) above the design maximum operating

temperature of the fluid in the solar energy system;

B. (1) 111 deg C (200 deg F) below the design maximum no-flow

temperature of the fluid attained in the collector provided

the collector manifold assembly is located outside of the

building and exposed to the weather and provided that relief

valves located adjacent to the collector or collector manifold

do not discharge directly or indirectly into the building and

such discharge is directed away from flames and ignition

sources; or

(2) the design maximum no-flow temperature of the fluid in

all other manifold and relief valve configurations.

The flash point of liquids used in Industrial occupancies as defined

by NFPA No. 101 [9], may be lower subject to the approval of the authority

having jurisdiction.

A "heat transfer liquid" is defined as the operating or thermal

storage liquid including water or other liquid base and all additives at

the concentration used under operating conditions. The flash point shall

be determined by the closed cup methods described in NFPA No. 321, Basic

Classification of Flammable and Combustible Liquids [2]. Liquids

classified as flammable (flash point below 100°F) shall not be used.

In systems using a gaseous heat transfer fluid, a flammable gas shall

not be used.

The design maximum operating temperature of the fluid is defined as the maximum fluid temperature that will be obtained when the heat transfer fluid is flowing through the system. The design maximum no-flow

temperature of the fluid is defined as the maximum fluid temperature

that will be obtained when the heat transfer fluid is not flowing through

the system.

Evaluation

An acceptable way of determining the design maximum operating

temperature is by the limiting action of control devices or relief

valves, or through theoretical or test analysis of the system. An

acceptable method of determining the maximum no-flow temperature is

presented in test method 7.2 (section 7. 2. 5. 2) of NBSIR 78-1305A [8]

where the design maximum no-flow temperature of the fluid is equal to the

plate temperature at stagnation. It should be noted that this method is

not valid for collectors with very low loss coefficients.

Commentary

Flash point values listed in manufacturers’ literature are commonly

average or typical values and some may be based on open cup flash point

tests. Flash point values used should be based on actual measurement or

16
certified minimiom values determined on representative samples by the

Pensky-Martens closed cup flash point test method ASTM D 93 for liquids

vrith a flash point at or above 93.4®C (200**?) or the Tag closed cup

flash point test method ASTM D 56 for liquids with a flash point below

93.4°C (200“F).

The flash point of aqueous solutions of organic liquids depends on the percentage of water in the mixture. In the case of ethylene glycol,

a flash point does not exist for certain percentages of ethylene glycol

with water. When these mixtures are slowly heated and the vapors allowed

to escape, the flash point of the mixture usually will be reduced,

ultimately approaching that of pure ethylene glycol. Care should be

taken that the flash point of the solution test sample is based on the

anticipated percentage of water during actual use of the liquid in the

system and not necessarily on the percentage as installed.

7 . ACKNOWLEDGMENTS

Appreciation is expressed to Mr. C. Veirtz who performed the tests

and to Mr. W. J. Parker who helped considerably in developing the flash

point criteria and whose suggestions resulted in more meaningful fire

tests of the solar heat transfer liquids.

This project was sponsored by the Department of Energy under the

direction of Mr. Arnold Weintraub.

8. REFERENCES

[1] Fire Protection Handbook, Fourteenth Edition, Section 3, Chapter 3,

pp. 3-19 through 3-21, 1976, National Fire Protection Association,

470 Atlantic Avenue, Boston, Mass. 02210.

[2] Basic Classification of Flammable and Combustible Liquids,

NFPA No. 321, 1976, National Fire Protection Association,

470 Atlantic Avenue, Boston, Mass. 02210.

[3] Standard Method of Test for Flash Point by Pensky-Martens Closed

Tester, ASTM D 93-73. American Society for Testing and Materials,

Philadelphia, Pa.

14] Standard Method of Test for Flash and Fire Points by Cleveland Open

Cup, ASTM D 92-66. American Society for Testing and Materials,

Philadelphia, Pa.

[5] Parker, W. J. and Lee, B. T., A small-scale enclosure for

characterizing the fire buildup potential of a room, Nat. Bur. Stand.

(U.S.), NBSIR 75-710 (June 1975).

17
[6] Lee, B. T. and Breese, J. N. , Submarine compartment fire study - fire performance evaluation of hull insulation, Nat. Bur. Stand.

(U.S.), NBSIR 78-1584 (May 1979).

17] Holton, J. K. , Interim performance criteria for solar heating and

cooling systems in residential buildings: second edition, Nat.

Bur. Stand. (U.S.), NBSIR 78-1562 (Nov. 1978).

[8] Waksman, D., Streed, E. R. , Reichard, T. W. and Cattaneo, L. E.,

Provisional flat plate solar collector testing procedures: first

revision, Nat. Bur. Stand. (U.S.), NBSIR 78-1305A (June 1978).

[9] Life Safety Code, NFPA No. 101, 1976, National Fire Protection

Association, 470 Atlantic Avenue, Boston, Mass. 02210.

18
Table

1.

Flash

point

and

fire

points

for

some

common

solar

heat

transfer

liquids

4J CM rH

m r—

00 CO 3 vO 3 3 u CO cn CM VO OV 3 vO 3 t-' •H 0 rH rH rH rH 3 CM CM 3 3 O s-/ A

di

a.3 (U U o o m

O

m

O

O o 3 O

O

•H 0 00 X)

m cn

m CO CTi

OO

O

a s— iH i-H CM CM cn cn CO •cj- 3 vO

(U

A

d. o

nac

03 rH 4J (—

CO C3^ rH CM cn CM 3 3 3 00

0) 3 O r>« \o CM CM

m vO CO 3 •sT C?v 1—

> •H o rH rH rH rH 3 CM CM 3 3

(UO

iH PLi a

x:

CO3 O

mmO lO lOO 3 3 3 3

tH o vO v£>

m o CM VO 3 vO 3 O

rH rH CM CM ro cn 3 •ct -cr 3 vO

CO3 4J CM \o CO

m 00 3 Ov CJV 3

0)

a 3 O

m

m rH rH cn cd vO OVO •sT 00

•u 3 •H o rH rH rH rH 3 3 CN CM CM u u O

CC3 pLi S -3 1 <U

CO CO x-s

M o 3 lO

mO U1 IdO 3 O 3 O 3

CO iH iH 0 CM cn <T r-» CO CM ON

O 00 3 CJ Pn rH CM CM CM CM 3 3 3

(1) Ph 3

•rHO3 3 3 3 O 3 O O 3 •K •iH CP o HC rH pc •H 3 •rH 3 U 3 3 CP

PI. •H

•H rH

X 3 U •rH HC o U 3 O O o •K rH 3 CM 3 3 3 Pc 3 O rH 3 O 3 PI 3 3 •H >s 1 3 1 1 1 3 X 3 O O PI 3 r3 to O O

HP rt 3 rH 3 Pi 3 3 3 3 3 3 U Pi g H3 O m X! CO 3 3 O 3

.H 3 O O. 3 3 CP 3 3 CO 3 Pc

PcO Pi •iH PC5 3 PQ PQ PQ 3 3 O 3 O C P) rH 3 >v 3 3 Pi o U O U 3 3 H3 3 3 3 0k •H 3 •iH 3 3 3 3 33 O 3 iH 3 3 3 3 3 3 >v 3 3

CC PI 3 •H Pi 3 3 3 0 T3 3 3 3 <PI U 3 3 3 3 3 3

PI tH 3 rH U-l 3 3 3 3 3 -3 3

HS rC fH 3 Pc 3 3 3 >v >v 3

00 3. HP Pc PI Pi Pc Pc 3 tH 3

•rH rH •H PJ 3 X 3 3 3 O

O 3

h-J < Q

U PP

U CP PP CP PP PP HC

19

Excluded

from

further

study

for

safety

reasons
S J

tfl rH (U O M

CO -H M fa

CO

0)

CO

cc) CJa

CO t3

•H3

4-1

4-1

(U -Cuo

4-1

COo

•H

4-> moo0I

<u&

fa

es

(U

cd H

cd 4J0 gj o e O 0

fa

(UCO0

CJ

CM

m

vo

COvO

COo

VO

CJ CJ CJ o O CM CM

CJ 00 00 00

03 o 0 0 0 II II •H 03 03 03 0 4J U

r—1 fa 00 vO VO 0 0

fa 6 CMmm 0 0 0 1 1 1 •rl •rl H K 4-1 4-t 4-1 43 H H H 0

PQ

U fa

(J o0

Vi0

+J0

Vi00

4J0

•HO

fa

Xim0

4-10

030mo

4-1

20

ill
Table

3.

Solar

heat

transfer

fluids

used

in

spray

tests

COa

d> Oi -u P s CJ P CJ *H I'U

I (U

CO M o

COc

(U PM

O

a

Xi

CO

cd

C-J Pm

uo

cvj LO

Pm o mCM

00 m 0C5 cn cy. CJN m

cn cn \0 <Ti o 00

iH iH t—

1

rH iH CM CM CM

m m o m o m o m

00 CM CTi o 00

CM CM CM cn CO '3‘ m

C3O

a•Hp

o

CO

<u Q

CJ •HP

0)c

0) o

u

(U p

CCj

6^O

•K in

1—

I

•H CJ cu O rH rH •H CM CO Mt- rH d

o d O cd G o 1 (U 1 1 1 CJ X

O fn X o X iH iH (U p 0) cu (U rH M C^ O CO X CO CO CO O •iH CO O cd a Cd Id cd CO

CJ (U CO cd PQ CO pq 0) rH O d rH z d >s P <1> O CJ CJ CJ CJ cu X!

•X3 1—

I

•H T) •H •H •H rH P

tn <U d d) d d d >> X d •H p •H •H •H e P (U <p o ip 4-4 4H rH •H P P4 I—

1

4H cd >P 4-1 4-4 Cd -d X fn cd p cd Cd Cd fn to

00 X p p p P P rH

•rl O p cd X cd (d Cd O O

m U Pm P:J a a a a a

21

Included

for

control

purposes
Table

4.

Case

A**

fluid

spill

fires I

x:w vO c o lT', UO a> c tn • 03 O o CM o^ o O'. CM

O. i-H o rH •H rH rH rH CM CM CO e ^

OJ U XJ

03 T3

•H3

1—H • fa Ce o 1 1 1 1 o c W’

1—}

U 0) o >

u-( 0 C o On CM rH -d- CO UO

s: *iH • • • « 4 4 4 4 0) w 0 o rH rH rH rH CN a^ 00 0 OJ *H i-H H 4hU U CD o > j"^ Mh 0 c 00 O 00 CN CM CO CM

CD •H • • • 4 4 4 4 •JC O; g 0 o o rH rH rH CM CT 0 Cd •H rH H M-i

for ing

/>—

Nc ro CN LO CM iH <r CM

OJ

w •rH « • • • • 4 4 4 4 0 03 O o o iH o rH CO 00 iH

•H rH H Uh Ua <U

03 0 /—N 4J 03 \0 vO \D M3 x; o vC C t-H o y-* o

TJ

cu

w

4J (D /<—S

QJ

Q

u :b o o O

O o C o o O 4-) rH *H P O 4-1 P W *H M so

1^

<3* o O LO rH a^ rH

f-H CJ CN a^ o rH CO r-- CM UO M-l 03 • o rH rH iH rH rH CM CM O

•H

a0 T3

•H 0)

m

m o m o mO UO 0 C -u fa o^ CM cn IT) CO o^ *H

hH o rH CM CM CM CO CO <r 1.1 0)a

D* <N 00m 00 CO o> UO 4J 3 • C-) LT) r*H m CO VD CJN O <r 00 M a XJ 0 rH rH iH iH rH CM CM CM (U fa v—

4J

CD x: OJ W (0 m IT) LO O UO O LO O UO rP O 03 fa <N 00 CM o^ o 00 <r +J rH 0 rH CN <N CM CO CO <r UO U 4-t s_x cu ).! tH CM CO 3 01

cd > c 1 1 I 1 X o o 0

eO rH CU OJ (U OJ iH <u u O (0 to (0 (0 •H /«—V o

03 o fd cd cd cd CO

H c U CQ fa fa fa cu tH •H OJ o rH 3 > O ;-i u 00 o CJ u u o 0) x:

•H T3 •H

H •tH •H •H rH P cu P 3 >> OJ 3 0) 3 3 3 3 >, cu c u

rH x: 3 •H

H

O •H •H •H 0 o u

fa 0) MH

a ^ MH MH MH rH rH •H cJ o

4J iH 4M 3 H MH MH MH Cd

O ra -H

x: Cd

H x: Cd Cd (d ?0O ^ iH o ^ tH x: H 4J a. U U U rH tH •H z

•rH •rH fd

X 3 Cd Cd Cd

O rH 0 CO *

XI o w fa fa 3 fa fa fa fal 00 fa ^

22 1i

Fluid

28

deg C

(50

deg

F)

below

flash

point.

Flame

in

contact

with

fluid.
Table

5.

Case

B**

fluid

spill

fires

00

C3

O. COO LO r^-

m

O LO o o 00O e m O 0> 00 1 CM CO 1 CO 1 vD lO 1 O 1 os 1 00 OS 1

(l) .H o I-H »-H r-H r-H I-H CM 1-H CM CM U U-t

4-J •H cd 0^ • C

•H /«—s CO

O CM o\ sD uoO

m

B CJ 1 00 1 CM 1 CM 1 CO 1 00 1 OS 00

m 1 OS so 0 I-H I-H r-H I-H 1-H 1-H CM CM CM o N—

u

U (U o > y«-N

«4-t o c O Csl vj- CM CO CO

OO CM

•H • • •>c • • •K • HC « • •JC * -K • K HC •JC

M

(U CO

B en CO CM r>. <3- SO UO

B <0 •H iH H ^

S—

M 0) O >

u-i o C (O CM CO CO o CM

(U •H •*< -KK • • •K • -K • • •K • •*<

KK •JC -JC

K

(D

g 6 CM <r < m SO e cd •HH

>»/

for ing x: a^ CM vO 00 o CO CO

O

<U (0 •H • • K * • HC • -JC • • •K • ^ • •JCa HC • • K £ cd iH r—i I-H vO CO CO <r lO 'd- o

•H 1-^ H ^

rH

4Jo d)

m lO uO lA

Cd S y—S • 4J Cd C «H O

CJ

s.y'

\0 ro f-H vD CO I-H 6 3 o CO r-H sO CO sO CO rH SO SO CO iH

TJ

(U

4.J 0^

Cdu ^ *H 2 0 0 OO o O o o o o OOOO o o O 0 0 O

O cw

CO M • CO

<u 4Jd

—NCM <JN CM CO iH CO Os c

i-H CJ r>. 00 o UO OS CM *H

(d • o I-H I-H I-H rH CM e

•H a. w e o

•H (1) y—S

mm o mO lOO lO rH

4-i 00 CM CJs

O 00 'dM 0 t-H I-H rH CM CM CO CO 4-1 Vw/ oo a y—V

00 lO 00 CO (7S C7S lO •iH

d • CJ i-H

m CO x> Os

O -d* 00

O xJ o r—t

r—•I-H I-H I-H CM CM CM 0) CL 'w' CL T3

<u x: 4J

CO CO y—S m lO o lO

OmO

m CO o cd 'Ct 00 CM CJs o 00 -d" 0) o CM CM CM CO CO m LJ CJ M-t 0) X4H

0)u 1—1

CM CO <r rH

C d) o cd > ; 1 1 1 O X o

>> o

I-H <D 0) 0) <u tH rH d) O CO CO CO CO PC •H o o Cd cd cd cd CO rH d

>> P3 pq CQ pq <u rH *H <u rH a >> o

T3 OO CJ

O CJa o 0)X

•H •iH T3 tH •iH •H •H f-H

U 0)

d

D OJ c QJC c c c 0)

C

a

1-H c •iH iJ o> •iH •H •HX

B o u

0) U-i CJX 4-t 4-^ 4-4 rH •H

U o

I-H 4-4 Cd -w 4-1 4h 4-1 Cd 'O »H

CdU

X Cd Cd Cd rH o X u •u CL U u U rH rH *|H IZ u Cd X Cd Cd cd Cd 0 O CO eu w c CL Pl. P-i Pm PL w

23

Fluid

56

deg C

(100

deg

F)

below

flash

point.

Flame

in

contact

with

fluid.
•HaX

•H3

•KU

(UXXu

VO

01 fH

"xH

003

•H3: • CO ro CN a 3 u irt 1 0 H 0 rH 3 VM 3 3

T3 3

•H3

rH • d

•H C7^ C3V 0 0 1 CM 0 rH CN 0

rH3 3 3 0 > 3 0 d 0 rH 3: •H • • K 3 CO s ro rH 0 3 s-/ rH

•3 ,3 H 33 3 3 0 > /—N 3 0 d 0 rH 3 •H • • 0) 0 s fO rH 0 3 A rH

•H rH H 3 3 60 0 3 3 3 /-*N 3: d 00 3 CO •H • • 0 3 s 0 3 3 s—/ rH H

0) OJ CD S a a 3 cd cd cd U 3 tH fH rH 3 0 MH fO 4-1 m 4H fO 3 3 • • • 3 rH rH 0 H 0 rH 0 0 3 rH fH rH U Cd cd 2 a a a

CO CO CO

'O33 3 3 3 v£) vO 3 3 0 3

CO 3

CM 3 I—1

CJ 0 CT\ 3 • 0 rH 3

•H (X 3 a

•H 3 in 0 3 3 CN 00 3 0 rH CN 3 a 00 on CJV 3 • CJ rH vO Nf 0 3 0 rH rH 3

Du 'w' ^33 ,3

toX /-*s in LO 0 0 3 Ci^ CN CO 3 3 0 CN cn <t

C-3 3 'w' CN

r*H 1

CD 0 CO u Cd PO 3

rH 3

'X OJD

a 3 3 •H 3 3 QJ d Ch 3 d H

(3 0) 4H 3 3

rH 4-1 3 CO >> Cd tH CJ u 3 tH

4-> cd 0 3 W PH PM 00

M

(U

4-1 33

•H0m

vwo

T3O

•H

l-l OJO-

•r(CU

CO -C

4J

4JU

CCJ 4-4 3O03

•H1H

iw

T3§0oo3

•H3U

•Hm

T)3

4JX

iHO

CO H

4-1 .3o

3- 33

CO3

CO

cu ^ ^ 60

33^ O2 ° U 3333333

CJOOO

!3

603

X3

vO

LT|

24
Table

7.

Case

D**

fluid

spill

fires }

(30 c

•H • to a. (0 §

4J

4J n3 cO •H3

iH • fa C

•HsM

l-i (U O >

«-l

O

(U (0 H fa

(U

O >

fa

O

(U

<U 5 H fa

l-i (30 O C

fa T-l

0) (0 H fa U (U

(0 0

fa (0 C rH O fa O o

vO o CM o o

CJ 1 03 o o O CH

m o rH 1—1 iH iH iH 0»

vr

vO

(33

r>od

foo

vO vO vO vO . 0) (0 4J 0) a>

(d 3 o o o o o o o fa rH •H .oi 3 o MH 3

CO •rH M 0m

rH

CM CM CM CM CM CM CM

rH o CM CM CM CM CM CM CM fa

cd • o o

•H

aa T3

•iH

d /—s

CM CM CM CH CM CM CM

O c 4J •r( M O )H Vw" 0)

C3.

a /-s CM 00

m 00m c^ fa

d • a

m 1—1

CO CO vD o\ o CO o o 1—1

rH 1—1 t-H rH CM (U

a fa T3

<D

X (U

cn CO \ m

mm o m

O LO 42 o ed CM 00 CM <J\ o fa rH iH 0 rH CM CM Csl m cn <r a (4-1 N—/ )H 1—1

CM CO 0)> C 1 1 1 1

iro O

t-H (U (U 0) (U (U 0 CO CO CO CO o

cd o Cd cd cd cd 3 o fO PQ PQ PQ 3 0 rH )-l M OO a o a o o

•H •H TJ fa •H •H •H 3 d >^ (U (U C CJ C o

rH x:

d •H fa (U •H •H •H

a

(U M-l

O (4-1 (4H o

4J rH (4-1 cfl fa (4H (H (4-1 x: Cd M x: Cd Cd Cd o

CjO iH JS fa Q.

u

u Z •rH ‘iH 4J cd X cfl cd cd Cd •K hJ O w Pl. fa c PM Pl< pH

25

Fluid

at

ambient

temperature.

Flame

in

contact

with

spi^
Oi) c

•HX• w a cd S

0) M-4 JJ 4J t3 n) •H3

f-H • fn C

•H0 U omI ino I I

CO

0) •H

14-1

T3•H3

M-l

1C*M

(U

CO

cd

CLJ

00

(U tH

.3

cd H

M

)-i 0) O >

4-4

O

0) CO 0 ed H iw

O

(N

VDO

^C

M

(U>O

cu (u a “ cd IH 14-1 3•H0 O

CN

m

K

•rlCU

CO

cu>o

-Q

ed 3 00 o c

IH -H

JC

(U CO 0 3 H r-4 H 14-4 3

•H0

00 COd

K 30

>4-1

4-4 O

T—4

•H

3.

O 3 3 0

4-4 3 3 rH O 14-4 C_J o o o 3330oo

V43H

-33

4-4 3 3 3

T—I *H o ^ W3 • •H a,

•H 3 3 4-I Uu

Cu3 • U 4-4 CU 33 JC M W O 3

1—4 r-4

C_5 IH

CM CM CM

rH iH rH

CsJ CM CM

CM CM CM

CM CM CM

h*.

CM 00 m CO

rH CM

m o O

CM 00 00

rH CM 3o

X)u3O 3 O 3

T3

M

U 3

•H 3 3 H r—4 3 3 tn rH X 4-4 3 X o X 1—4 1—4 4J 3 4J 3 O

XiM

X fn

O

bD 1—4

4J cu r-4 >1

H ’(-4

X 3 O r-4 XI o W 3 34 60

0) • 3 •H 3 44H 4J33 0)

•rH H) 0 Cd rH m 0 1—4 W

•H UHO 0)W) 3 M O Cd

•r4 hH U3

Or • a) 4J33 4->

4-4 CdH 3 CD X 0*

4-4

B

0)

M 4J 3> 4J O C

0) 3 •H 33 e 3 cd MM u 3 cd OOo •H o rH z

26
Table

9.

Fluid

spill

fires -

ethylene

glycol

and

ethylene

glycol-water

mixtures

i|

i|

•H

x: • tn

(D 6 iH

0) >4-1 M

>0

•H3 U

O

(T>

O

0^ I I b c

•Heo u oo I CTi

O

>4-1

a)

0)>0

Si

(0

(0

>4-1 c

•He a\ * o• * *

ro

V4O

<4^

0) .§

tH

V4

0)>O(1) e

>4-1 cHB

00• * * o o

roA

4c o

>4-4

a)

Eh

C

•H

s:m

(0

<4H cHE

tN

m o >0

K 4C PO 0) m e p (3 C r-4 o >P u

VO >0 VD VO VO VO

<U -P (1)

(t) P

iH *rH O >4-1 cn

X

fd • •H Qc

•p e

rH 0) C -P

Uo

Qc3O

>0

(U

U)OU >4-1

u

73

•r43

r-H o O

OO o o o O O (N fS CN

o> <n CD VD vD >o

vn If) If) If) If) in

cn cn CD Hd" HJ*

1—4 r-4 rH rH rH rH

00 00

1—4 4 4 rH 1 1 1—4 rH

If) If) 1 1 4 4 (N CS

1—4 rH rH rH 0 O 0 0 U CJ u u

>1 >1 >1 >.

1—4 rH rH rH rH rH 0 0> O' O O' O' u o

>1 0) <U >1 <U <u

1—4 c * c * rH

C * C 'll On (U * 0) •4C 4J> (U * (U -ic rH P rH P rH P rH P o >1 <u >1 OJ O >1 (U >1 <u c Si -P x: -p c Si -P Si -p

0) -p (d

p (d (0 (U -p Id •P Id

1—4 0) s <u s i-H 0) S 0) >

>1 0) >1

s: OP dP dP dP tn o: dP dP dP dP 4J If) If) a CD Id -p If) Lf) o o

|jL| (N vn lO

u 4y (N in in P

0)>o

<uuc

(Upp3UUOOZ P

(dp

-PC

(Uucou

td •HP

•HCM

•4C * 27 i

the

test

period

of

10

minutes.
Table

10.

Flowing

fluid

fire

test

(pilot

flame

only) -

light

hydrocarbon

oil

O ^ CU p a > 4—V O o O CM •H CM o

CUO 43 CU 4“ CM <1-

a CO CO •H cd V—' H r-l cp

bO o d p •H43 CJ o +- CM

cu CO cu CM 4- rH

CJ

a cd CO o •H rH s-/ (N H M-l un

<PO 0m • 43 •K o CM CM CN (24 O iH o CM CM iH a d 0 r—<

rH

<U *H

OOO P d. O O O 04 (24 H CM 04

CCj • (U o O

4J •H

O CU

d

d

a P TU P>4 CM CM

•H •i4

O (^

O

d

a

H

4=

CO

cd rH

VWiH 4C

•i4 •K O CJ CM VO VO

•K o 'Cf sr 1 do bO iH it 42 P d •H a

cd •H Oi ^ m CO

CCJ 43 CO (P o H rH 1 O cu CO o iH r—1

rH

O cd

>-l

d iH T3 p 4-1 cd •K 43 M P /~v K

cu

O <u CJ

m CM r«^ 00 P (24 bOo vO vO VO

43

a CU P

bO (U

a cd •H H •H 43 •K P CJ K

CO c» CO rH

•r( pi4

m (^

(O 0 iH rH rH rH

s-/

a (U iH rH rH (U o N iH rH rH bO o •H cd Cd Cd P

Pi CO

aaa cd CO CO CO PI

28

•H

4J

CO

0) 42

CO

CCJ

•H>OO

CU T)a

cO

•H

a.

Crt

4J

CO

cu 4J O

VO

(U 43

4J

cOu

(Ua

ccJ cu Oh

Oz+-

+-

test

period

of

60

sec
Table

11.

Flowing

fluid

fire

test

(pilot

flame

extracted-naphthenic

oil 1[II I I HCO Ii

P4

O <U 44 > o 0 o o 0

3J

O 43 (Um 4t CN +-

c» 0 O CO CO '^r >cr

m 4-

cn •H C4 cd V—/ iH H .H

(44 0O t»0 00 O (3 CN 44 ^ o

43 <u lO <r CN 4-

<U CO CO 1—1 4— 0 cd •H iH H M-4

U

CJ •HO

o< 9C

4C 4= CN nT

CO CJ 1 cn CO rH

cd o rH I—1 r—1

<—1 *

M-) 00C t—1

1—1

•H •H

K

•H 43

a * O CU CO CO OS CO CN

P4 Cd 1 SO St

CJ 3 fH o CN CN CN

•H 44 (4-1 '— C Cd

CU 44 (44 43 CU o

44 C4, 43 e 0) 4C a <u e •JC cd H -H rH rH I—1 CN

CJ 44 (U CJ so

m CO OOo t—1 I—1 1-4 rH

'O 44 >4 ^ cu Cd cd 44 43 o o 4C

cd CO

K

C4 •H C3S tH CO OS

44

Q f*4 CO CN

O so

X o CO CO CO CN

0) iH

•H

COO

4J

CO(U 43

COcdc

•H>

C3O

iJ

CO

(Uo

0>

CO oso

<u x:u

cu>o

(U3u

cd

cu&cu

4*!cdcu

•JC K

(U>o

0)os

CJ

CJoo 1 t

29

test

period

of

60

sec
Table

12.

Flowing

fluid

fire

test

(pilot

flame

only)

polyalkylene

glycol

I o o cu o 4J >

CJV a o o

'Jt Si O Xi cu +- + •H

es) i o CO CO +- + +-

•H ccJ H iH

IH

OO

00 00

•cl- o d

4-1 •H o •K

(U •K CM +-

S!

CO CO •K +

i CCJ V—

/

•H

•U H CH d

•rlO

a

•K a

xi •K

CO u m MT d o •a- CO cn

tH CM CM CM tw 00 a

d iH

r—

1

•H rH

•H xi •H O cu CO du u CCJ CO •K a

iH d H /~s •K K

O 4J CH pH CO 00 a\

O ccJ o r>. m 00 M »H

rH (U o

00 a

a (U cu cu K •K d H •H K •K

cu 4J o (N CM

iH (U O v£) Mf cn

4J 00 CM CM CM

cO H

CCJ

CCJ .d

>v CJ rH CO O •H •K K

o ^ 4C •K pH •O’ f- Ov

o o VO 00

CO mT

(U iH

*H

i-i

COo

4J

CO

(U

CO

CCJ

.s>

d

o

iH

•H

CU

C/3 K

4J

CO

(U

4-> O

(U

CO oVO

0) .d

4J

cu>

o

cud

4J

CCJ

ccJ cu

PLI a

it

00d

•HXi

CO

cU iH

<4^

d

cu 4J

4J •H

<U U

dH

K

•K•K

30

test

period

of

60

sec
Table

13.

Flowing

fluid

fire

tests

(pilot

flame

only) -

ethylene

glycol

and

glycol-water

mixtures

OJu

oo E ^ o >

cq

O

O

nu x: o w

(0

O Cfl

to E (U c O to -H

14-1 cd CO ^ 03

0)

a .H e CO M-i •H ‘rH H XJ O

•H 4J UM CO 3 03 O C

i-H *H

4-1 . 0) x: a e w c E -H cd

(d o 4J 1—I

Cu 4^ 4-1

0)CO 4J 4-< CO M cd o c • 0) x: a E w E *H cd

a; 4-4 rH

XJo to

•r^

C

U -H

0)Q. -Ho

0) X) E

•H 4-) H O • 4-t a o E

(U oE c

03 H

03toU

03 Xu

CO

•K • to

a. 4J c E 03 -H

03 CO »H

AJ cO

O

d 4J

cd 03 4-( H O

03 ^ c

Cd 03

03

03 03 ^ I 3

--I 4J •H x: o X

CJ -H

03 >> E

to

C 4-> 0 AJ •H cd 44 tc iH

4-> o O'

O

•H •H c •H CJ 3 CO cd 03 X X o a. E (0 X a •rH cd to E AJ AJ 0 cd 4-1 u

03 c to 4-t o u 0 tfl ^H

•H Cd c o

AJ

X 03 •H CJ •H •H u E X 3 CO CO •rH CO rH o •H AJ cd to

CLi a.

X 1^ E AJ 4-t s^s O AJ Cd o Cd

to

•K

*C<•

CNO

00

O

C^

•Km

X

00

-K 4< -K

•ic -JC -K -K CM CM m O

tn to r*^ CO

CM CM CM CM

4C00

O

m 0> 00

CO 00

CM CM CM CM

00

00

CM

CM

Oo

o^

C7^ CM

O

m IX o

CO CO C3^ o

00

CMX

CM

CO

CMOooo o o

o^ o o

vO

CM

•K

•JC <J- CM CM

<r

m 00

CM CM CM CM

<T'

00 CM 00 O

CM CXoXo o o o O C7^

rH

X iXX

X

XX

X 03 03 E 03 *—1

1—

X

X

XXXX

X to to 0 N Cd cd Cd Cd cd cd cd cd Cd M U o •rH E E E E E E E E E Cd Cd OC CO CO CO CO CO CO CO CO CO CO X X

(U

Cl. 3

Cd XX

03O

Cl. Cd>X

03>u

03CO Xo

CO <

•X oX

31

***Fluid

composition

at

30

sec

ttNo

flashing

observed

up

to

60

sec

test
Table

14.

Flammability

of

fluid

soaked

insulation

32
/

I

Figure 1. Active solar energy system

33
Figure 2. Reduced scale room fire test

Figure 3. Fluid spill test pan with spiral gas burner in place

34
UJ

-JNNOZ

Li. o

UJz

in “*

ui oc S Ui ! s t “ od“ z

Hi

=» £ UI ? S

UJZou><

GC

CL

(/)

UIgUJZo<

UI<

UJo

35

Figure

4.

Spray

test

setup
O

CaM

A

•

Casa

B,

6kW

flam#

A

Casa C

3. ‘isai 3Uld VVOOU Nl 3UniVU3dM31 HSVld

o>u

3

bO

•H

36

CLOSED

CUP

FLASH

POINT

TEMPERATURE,
NBS-114A (REV. 9-76)

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 79-1931

Z, Acc^s.ioi^ Mo.

4. TITLE AND SUBTITLE

Fire Experiments and Flash Point Criteria for Solar

Heat Transfer Liquids

5. Publication Date November 1979

7. AUTHOR(S)

B. T. Lee and W. D. Walton

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS Pioject/TaskAVork Iteit No.

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS fsrreef. City, st^te, ziP)

Department of Energy

Washington, D.C. 20545

13. Type of Report & Period Covered Final

liiiiiiiiiliU 15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Software Summary, is attached.

16. ABSTRACT (A 200~word or less factual summary of most significant infonnation. If document includes a significant bibliography or

literature survey, mention it here») To help provide a rational basis for developing flammability criteria for

heat transfer fluids used in solar energy collection systems, fire tests were

performed using simulated accident scenarios involving spills, flowing leaks,

spray leaks, and soaked insulation. These experiments indicated that the flash

point temperatures, as measured with the Pensky-Martens closed cup apparatus,

are close to the minimum temperatures at which pools of the fluids will support

a flame when they are exposed to a small pilot igniting flame in a room. The

heat release from moderate sized burning pools of these liquids is sufficient

to cause flashover in a room.

Interim flash point criteria of at least 28 deg C (50 deg F) greater than

the maximum operating temperature and not more than 111 deg C (200 deg F) below

the maximum no-flow temperature are proposed to reduce the risk of fire in the

use of solar heat transfer liquids.

17. KEY WORDS ('six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name;

separated by semicolons)

Fire prevention; fire tests; flammability; flash point; heat transfer fluids;

insulation; leakage; solar collectors; solar energy.

19. SECURITY CLASS 21. NO. OF

(THIS REPORT) PRINTED PAGES

UNCLASSIFIED ^ 40

20. SECURITY CLASS 22. Price (THIS PAGE)

$4.50

UNCLASSIFIED

18. AVAILABILITY HUnlimited

I I For Official Distribution. Do Not Release to NTIS

I I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No, SN003-003- [2 Order From National Technical Information Service (NTIS), Springfield,

VA. 22161 USCOMM'DC
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